The proposed project will initiate a novel, interdisciplinary investigation into the ontogeny and phylogeny of neural and perceptual processes underlying vocal communication. Given the complexities of vocal communication and language, it is becoming increasingly clear that an understanding of vocal perception can only be achieved through a multidisciplinary effort. The present project will bring together experts from the fields of psychobiology, comparative behavior, electroencephalography, and linguistics, and will employ a wide range of methodological approaches. The ultimate goals are to gain a clearer understanding of 1) the constitutional and environmental contributions to the development of vocal perception, 2) the specific neural mechanisms and perceptual processes underlying vocal communication, 3) the features or attributes of acoustic stimuli to which these mechanisms may be tuned, and 4) the phylogenetic emergence of these perceptual mechanisms. The proposed work, representing a critical step in this direction, will examine the development of perceptual reactions of infant chimpanzees to natural and synthetic vocal stimuli, through the combined use of autonomic measures, cerebral event-related potentials (ERPs), and Magnetic Resonance Imaging (MRI). Autonomic responses to vocal stimuli will reveal basic patterns of functional reaction to the acoustic stimuli, and ERPs will provide indices of the neural events underlying stimulus processing. In addition, the ERP measures, coupled with MRI reconstructions, will provide critical information on the cerebral distribution of electrical activity evoked by the experimental stimuli. A further understanding of vocal processing in non-human primates may not only enhance our appreciation of social communication in these species, but may contribute to our understanding of the underlying neural and perceptual mechanisms for vocal perception in humans. Thus, information gained in these studies may lay important groundwork for an understanding of the neurodevelopmental bases of normal and dysfunctional speech perception in human children.